Hollow cylindrical members such as piping and tubing are used to transmit fluids in a wide variety of applications. In some applications, economic considerations, maintenance time and other factors make it preferable to remove a damaged or defective section of piping or tubing, and replace it with a new section, rather than remove the entire length of tubing involved.
One method of replacing a damaged section of tubing from a length of original tubing involves first cutting the original tubing on either side of the damaged section, removing the damaged section of tubing, deburring and polishing the stub sections of original tubing which remain after the cut and then welding, brazing or otherwise permanently affixing a new, replacement section of tubing to the stub sections of original tubing.
In the prior art, the cutting operation is normally performed with a cutting blade which is positioned in engagement with the outer wall of the tubing and then rotated or moved laterally to cut from the outer surface to the inner surface of the wall of the tubing. This produces two stub sections of original tubing on either side of the damaged section of tubing which is removed. The cut ends of the remaining stub sections of original tubing may have burrs or other surface irregularities as a result of the cutting operation. These are removed by one or more deburring tools having cutting blades or an abrasive surface adapted to contact the end of such stub sections.
Depending upon the type of joint to be made between the replacement section of tubing and the stub sections of original tubing, a chamfering tool may be employed to form a chamfer on the end of each stub section of tubing. A polishing tool is then used to buff or polish the outer wall of each stub section in preparation for the brazing or welding operation in which the new or replacement section of tubing is permanently affixed to each of the stub sections of the original tubing.
For example, if a butt weld is employed, each end of the new, replacement section of tubing is placed over the chamfered end of a stub section of original tubing and a bead of brazing or welding material is then placed around the circumference of the joint. Alternatively, a fitting adapted to receive one end of the replacement tubing and the finished end of the stub section of original tubing is welded in place with a weldment extending about the outer circumference of the tubing.
The problem with the technique described above, and similar techniques for replacing a damaged section of piping or tubing, is that all of the operations performed require ready access to the tubing so that the tools involved can be manipulated to perform their respective functions. The cutting tool, for example, must be positionable against the outer surface of the wall of the tubing to cut therethrough. The deburring tool, chamfering tool and polishing tool must all be manipulated against the cut end of the stub sections of original tubing in order to perform their respective operations. The acetylene torch or other means for heating the welding or brazing material must also be freely manipulable in the area of the joint between the stub sections of original tubing and the replacement sections.
In some applications, access to the tubing for performing any of the operations described above is difficult, if not impossible, using prior art tools and techniques. For example, the tubing employed in the turbine of a jet engine for carrying lubrication, coolant, fuel or instrumentation cannot be directly accessed except through an opening in the turbine case without disassembling the turbine. Disassembly of the turbine is a difficult operation involving a substantial amount of maintenance time and expense.